<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./css.css/css.css">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/3.2.45/vue.global.min.js"></script>
</head>
<body>
    <div id="App">
        <div>
            <input type="text" v-model:value="counter" class="a">
        </div>
        <div class="contect">
            <div class="item" @click="counter=counter+0">0</div>
            <div class="item" @click="counter=counter+1">1</div>
            <div class="item" @click="counter=counter+2">2</div>
            <div class="item" @click="counter=counter+3">3</div>
            <div class="item" @click="counter=counter+4">4</div>
            <div class="item" @click="counter=counter+5">5</div>
            <div class="item" @click="counter=counter+6">6</div>
            <div class="item" @click="counter=counter+7">7</div>
            <div class="item" @click="counter=counter+8">8</div>
            <div class="item" @click="counter=counter+9">9</div>
        </div>
    </div>

<script>
    const Counter = {
        data() {
            return {
                counter : 0
            }
        }
    }

Vue.createApp(Counter).mount('#App')
</script>
</body>
</html>